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Hastings and Prince Edward Public Health

Respiratory Syncytial Virus Vaccine (Synagis) FAQs

Synagis® (Palivizumab) is a biologic medication that provides antibodies to protect children who are at high risk of becoming infected with respiratory syncytial virus. With vaccines, your child creates their own antibodies for long-lasting protection; however, when the antibodies are from a medication, they need up to five injections to keep them protected during the winter months.

What is respiratory syncytial virus?

  • Respiratory syncytial virus (RSV) is a highly contagious viral infection, common in the winter.
  • RSV is the most common respiratory illness in children under 5 years of age and infects nearly all children by their second birthday, with the highest rate among young infants.
  • Most children and adults who develop an RSV infection have mild symptoms for one or two weeks of a “bad cold,” such as fever, nasal congestion /discharge, and a cough.
  • However, high-risk infants, including premature infants or those with chronic lung or heart disease,are more likely to have severe breathing problems with an RSV infection, such as wheezing (bronchiolitis) and/or pneumonia.
  • Premature babies tend to have smaller lungs and airways, so an RSV infection is worse for them; also, infants born at 32 to 35 weeks gestation have only half as many of the mother’s protective antibodies as full-term babies since they receive them mainly in the last trimester.
  • RSV is the number one cause of hospitalization in children under one year of age.
  • For high-risk infants, Palivizumab/Synagis® is available to prevent them from being infected with RSV, and it can reduce the rate of RSV hospitalizations by 78% for infants 35 weeks or less gestational age, and 80% for infants 32-35 weeks gestational age.

Who is eligible for RSV prophylaxis with Synagis®?

To be eligible for the RSV Program, the infant must:

  • meet the RSV Program’s listed clinical criteria, for example
    • all infants born under 33 weeks gestational age are accepted
    • preemies born under 36 weeks gestational age and 6 months of age or younger at the beginning of RSV season are accepted
  • be a resident of Ontario and insured under the Ontario Health Insurance Plan (OHIP)

Who should not receive Synagis?

Your infants should not receive Synagis® if they:

  • have an allergy to any of the components: palivizumab – (no preservatives); non-medicinal ingredients: chloride, glycine, histidine, mannitol, water for injection; vial stopper does not contain latex.
  • have ever had a severe allergic reaction to Synagis® before, including
    • severe rash, hives, or itching skin
    • swelling of the lips, tongue, or face closing of the throat, difficulty swallowing, difficult, rapid, or irregular breathing
    • bluish color of skin, lips, or under fingernails (if unusual for your infant)
    • muscle weakness or floppiness, unresponsiveness (if unusual for your infant)

What are the common side effects of Synagis®?

  • Some infants may be sore, red,or swollen where the needle was given.
  • Some infants may develop a fever or a rash, feel achy or irritable,seem tired,or have the symptoms of a cold.
  • Tylenol® / acetaminophen (or liquid ibuprofen, if your infant is over 6 months of age), may be taken afterwards, as directed, to reduce discomfort or fever.
  • Children under 19 yrs of age must not be given ASA, Aspirin® or salicylates.

What else do I need to know?

  • RSV treatment usually starts in the third week of November and ends around April 1st.
  • Synagis® does not protect against the flu, so unless there are medical reasons not to vaccinate against the flu, every child 6 months of age and older should get a flu shot, and two doses are recommended the first time, at least 4 weeks apart.
  • It is recommended that Synagis® be given 24 hours before or after a routine vaccination/flu shot for proper monitoring of side effects,but if this is not possible due to the parent’s schedule, the shots may be given on the same day;the research says it is okay.
  • On very rare occasions, life-threatening anaphylactic reactions have occurred after Synagis® (less than 1 case per 100,000) and fatalities have been reported; however, the Hospital for Sick Children states “the risk of [Synagis®] causing serious harm is extremely small. Life-threatening allergic reactions are very rare. The most common side-effects are fever, irritability, or redness at the injection site.”
  • The benefits of up to an 80% reduction for preemies in the number of hospitalizations for RSV, after Synagis® preventative treatment, far outweigh the risks of the medication.
  • Do not delay or miss a dose of Synagis®, if at all possible.
  • Tell the nurse if your infant has any bruising or bleeding problems, since Synagis® is given by intramuscular injection.
  • If your infant is taking a blood thinner, e.g. enoxapram, apply pressure to the site of the injection for at least 5 minutes afterwards.

When should I seek medical help after my infant receives an injection of Synagis®?

  • If your infant experiences any unusual side effects, please seek medical attention and notify public health, as well.
  • Call 911 or go to Emergency at a hospital right away if your infant has any of the following symptoms after receiving Synagis®:
    • swelling of the face and neck or problems breathing
    • hives and itchy, reddened skin
    • unusual bleeding at the injection site
    • unusual bruising or groups of tiny read spots on the skin

RSV Vaccine Fact Sheet printable pdf

Need More Information About Respiratory Syncytial Virus Vaccine (Synagis) FAQs?

Talk to your health care provider or call our Immunization Program at 613-966-5500 or 1-800-267-2803, ext. 221.

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Appointments for individuals 5+ can be booked through the provincial vaccine booking site, or by calling 1-833-943-3900 from 8 am to 8 pm, 7 days a week.  

Due to limited supply, HPEPH will initially be prioritizing available bivalent vaccine for residents and workers at identified highest-risk facilities.  Some HPEPH vaccination clinics MAY offer the bivalent vaccine, as availability allows. Vaccine clinics in Hastings and Prince Edward Counties will continue to offer monovalent vaccines (the same mRNA vaccines given as the primary series) for all eligible individuals until a steady supply of the bivalent vaccine is available.

Visit the HPEPH vaccine booking web page for details.


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